List *List_merge_sort( List* words , List_compare cmp){
/* find middle , split into two lists
* recursively do this ,until only one left
* then recursively merge two lists
*/
int middle;
static int i = 1;
List *second;
if( words->count == 0 || words->count == 1 )
return words;
middle = words->count / 2;
second = List_split( words , middle);
assert( second != NULL );
/*after this words stores the first part before middle
* and second begin with middle-th node
*/
words = List_merge_sort(words , cmp);
second = List_merge_sort(second , cmp);
// printf("times: %d\n" , i++);
/* List_travers( words);
List_travers( second);
*/
List *dest = merge_two_parts( words , second , cmp);
log_info("now merge");
return dest ;
}
void merge_sort_seq(Array<Item>& a, int_t left, int_t right, ResultArray<Item>& result, int_t result_offset, TmpArray<Item>& tmp_array, int_t tmp_offset, const Compare_fct& compare) {
if (left == right) {
return;
}
if (left + 1 == right) {
result[result_offset] = a[left];
return;
}
int_t mid = (left + right) >> 1;
merge_sort_seq(a, left, mid, result, result_offset, tmp_array, tmp_offset, compare);
merge_sort_seq(a, mid, right, result, result_offset + mid - left, tmp_array, tmp_offset + mid - left, compare);
merge_two_parts(result, left, mid, result, mid, right, tmp_array, tmp_offset, compare);
std::copy(tmp_array.begin() + tmp_offset, tmp_array.begin() + tmp_offset + right - left, result.begin() + result_offset);
}